Peristaltic fluid pump



M rc 8, 1969 E. R. CORNEIL 3,433,171

PERISTALTIC FLUID PUMP Filed Nov. 23, 1966 f 2 MW 02 BY. w M

March 18, 1969 E. R. CORNEIL PERISTALTIG FLUID PUMP Sheet 2 of2 FiledNov. 23, 1966 United States Patent 3,433,171 PERISTALTIC FLUID PUMPErnest R. Corneil, RR. 1, Thorold, Ontario, Canada Filed Nov. 23, 1966,Ser. No. 596,533 US. Cl. 103149 16 Claims Int. Cl. F041) 43/08, 17/02ABSTRACT OF THE DISCLOSURE A peristaltic pump in which positive andnegative pressures are produced by distortion of a resilient tube. Oneuse of the pump may be to pump blood, for example, in such as artificialheart and lung machines.

In existing forms of peristaltic pumps resilient tubes or cylinders havebeen used, the resilience of the material forming the tube or cylindercreating the necessary negative pressure to draw in a fresh supply offluid after fluid has been expelled by distortion of the tube orcylinder. Therefore it was essential that the tube be not only flexiblebut have the capability of recovering its undistorted shape afterdistortion. The recovery forces control the negative pressure obtainedand set a limit to the rate at which fluid is drawn into the pump. Anincrease in recovery force, with a consequent increase in negativepressure, can be obtained by increasing the wall thickness of the tubeor cylinder of the pump. However the increased thickness requiresexcessive power for distortion, creates undesirable heat and causesrapid deterioration of the tube materials. There results a limit to thepracticability of the process to laboratory sized equipment.

Although resilient tubing is manufactured with given wall thicknessesand internal diameters, the tolerances are quite wide. Further, both thewall thickness and the internal diameter are subject to change underservice conditions. The efliciency of the pumps is dependent upon thedistortion, e.g., occlusion, of the tube, and overdistortion of the tuberequires excessive power and limits tube life. It is, therefore,desirable to control the forces applied to the tube.

The positive pressure developed is limited by the strength, andthickness, of the resilinet tube walls and on occasion the walls balloonand burst. This limits pumps of this form to relatively low pressures.Also, it is desirable to match the wall thickness with the desiredpressure to avoid using a greater wall thickness than necessary with theconsequential increase in power requirements.

It is an object of the present invention to provide a fluid pump inwhich the positive and negative pressures are produced by the distortionand recovery of flexible tubes or cylinders, without relying onresilience of the tube or cylinder to cause recovery.

Another object is to provide a fluid pump using the distortion andrecovery of a tube or cylinder for producing the necessary positive andnegative pressures, in which the forces for distorting the tube orcylinder can be adjusted to produce a desired distortion independent ofthe thickness of the wall of the tube or cylinder.

Another object of the present invention is to provide an apparatus forconverting rotary motion into a reciprocal motion for distorting thetube, and a further object is to provide means for controllably varyingthe cycle of operation whereby the distortion of the tube is nonuniformduring the cycle, there being a dwell period at maximum distortion, andthe production of a maximum pressure.

The invention will be readily understood by the following description ofcertain embodiments, by way of example, in conjunction with theaccompanying drawings, in which:

3,433,171 Patented Mar. 18, 1969 ICC FIG. 1 is a longitudinalcross-section through one form of pump, on the line 11 of FIGURE 2;

FIGURE 2 is a cross-section on the line 2-2 of FIG- URE 1;

FIGURE 3 is a cross-section on the line 33 of FIG- URE 1, to a slightlyreduced scale;

FIGURE 4 is an end view, partly in section, in the direction of arrow Ain FIGURE 1;

FIGURE 5 is a side view of one form of tube for use in the pump;

FIGURE 6 is a cross-section on the line 6-6 of FIG- URE 5;

FIGURE 7 is a longitudinal cross-section of another form of tube for usein the pump; and

FIGURE 8 is a cross-section on the line 8-8 of FIG- URE 7.

The pump illustrated in FIGURES 1 and 2 comprises a housing 1 having anend cover 2. A camshaft 3 is rotatably supported in the end 4 of thehousing 1 and in the cover 2 by bearings 5. The camshaft has a series ofpairs of cams 6 and 7. The cams 6 and 7 forming a pair are displaced toeach other and each pair is displaced relative to adjacent pairs, sothat successive pairs are equally spaced around a circular locus. In theparticular example illustrated there are twelve pairs of cams 6 and 7,each pair displaced 30 relative to the adjacent pair.

Mounted on the cams 6 and 7 are movable plates 10 and 11, respectively.Each plate 10 has a cam slot 12 within which turns the cam 6, and alsohas a leg 13 extending through one wall 14 of the housing 1. Each plate11 also has a cam slot 15 within which turns cam 7 and a leg 16extending through the wall 14 of the housing. The legs 13 and 16 aresupported for reciprocal movement by a bearing strip or support 17. Thebearing strip or support is rotatably supported in the wall 14 for apurpose explained below. It is readily inserted in a slot in the wall 14from the end when the cover 2 is removed.

The slots 12 and 15 are mirror images of each other and the pair ofplates 10 and 11 for each pair of cams 6 and 7 are immediately adjacentand reciprocate in opposite directions. The form of cam slot 15 in plate11 is readily seen in FIGURE 2, and the form of cam slot 12 in plate 10is seen in FIGURE 3.

Each plate 10 and 11 has a slot 18 in its lower end. A rotatable bar 19passes through all the slots 18 in the plates. The bar 19 is supportedin the end 4 of the housing 1, and in the cover 2, by bearing sections20 which are eccentric to the main portion of the bar. A control lever22 is attached to the end of the bar which extends through the cover 2,the lever attached to the bar by a pin 23.

The bar 19 acts in cooperation with the bearing strip or support 17 toguide the plates 10 and 11 in their reciprocal movement. The controllever 22 can rotate the bar 19 for a purpose which will be describedlater.

Legs 13 and 16 carry at their ends, remote from the related plate,pressure bars 24 and 25 respectively. As will be seen in FIGURE 1,pressure bars 24 on legs 13 are on the remote side of pressure bars 25on legs 16, relative to the housing 1.

The pumping member comprises a flexible tube 30 having two radiallyextending fins 31 and 32. The fins 31 and 32 are diametrically oppositeeach other and in a plane parallel to a plane passing through the axisof the camshaft 3. A series of holes 33 are formed in the fins 31 and 32for the reception of the pressure bars 24 and 25. The ends 34 areattached to inlet and outlet conduits 35 and 36.

As the camshaft 3 is rotated, the cams 6 and 7 rotate within the camslots 12 and 15 causing the plates 12 and 16 to reciprocate, moving thepressure bars 24 and 25 towards and away from each other. As thepressure bars move towards each other they press upon the tube todistort it, whilst movement away from each other positively returns thetube to its original cross-sectional shape. The distortion of the tubeis progressive along the tube, in the manner of a travelling wave. Thepositive action to re turn the tube to its undistorted cross-sectionimproves the operation of the pump as there is no reliance on theresilience of the tubing material. The thickness of the tube wall hasonly to be sufficient to withstand the maximum positive pressureproduced during pumping. The negative pressure, or suction, produced bythe return of the tube to its undistorted cross-section is independentof the tube resilience and can be positively controlled. Any variationin the physical properties of the tube material will not affect thepressure produced.

In the operative position as shown in FIGURE 1, the pressure bars 24, 25at the left of the figure are at their closest position while thepressure bars in the centre are at their maximum spacing. As the pumpoperates, by rotation of the camshaft 3, the pressure bars to the rightof the centre will move apart while the pressure bars to the left willmove towards each other. Thus the volume of fluid within the tube ismoved to the right. Simultaneously, the pressure bars at the extremeleft will be moving apart creating a low pressure area into which fluidis drawn.

FIGURE 2 shows the tube 30 distorted to a condition where the gapbetween the opposed walls is almost at a minimum. This gap width willoccur at this phase position for each revolution, as long as the platesreciprocate in the plane set by the bearing strip or support -17 and thebar 19 as they are positioned in FIGURE 2. The gap width between theopposed walls of the tube and the gap width between opposed pressurebars 24 and 25 can be varied by the control lever 22.

The control lever 22 has a screw 40 extending through the end remotefrom the bar 19. The tip of the screw enters indents in a boss 43 formedon the cover 2. By loosening the screw 40 to withdraw the tip fromindent 44, the control level 22 can be moved to rotate bar 19 relativeto the housing 1. As the bar is supported eccentrically by the bearingsection 20, rotation of the bar 19 shifts the plane in which the platesand 11 reciprocate. Shifting the plane of reciprocation also alters therelative positions of the cams 6 and 7 in the cam slots 12 and 15. Whenthe control lever 22 is moved to the extreme right, as seen in FIGURE4,the pressure bars 24 and 25 approach closer to each other in the oneextreme position. Thus the gap width between the opposed walls of thetube is reduced. In addition, or alternatively, to varying the minimumgap between the opposed walls of the tube, variation in the minimumdistance between pressure bars 24 and 25 can be used to compensate forvariation in the wall thickness of different tubes. The variation in theplane of reciprocation of the plates 10 and 11, and thus of legs 13 and16, is accomodated in the bearing strip 17 by the strip being rotatablysupported in the 'wall 14.

The displacement of the point of contact between each cam and itsassociated cam slot, relative to the rotational axis of the camshaft 3',does not follow a linear curve. The reciprocation of the plates 10' an11 slows down as the displacement of the cams approaches maximum. Thereis thus produced a considerable mechanical advantage and the forceapplied to the tube increases substantially as the gap between thepressure bars approaches the minimum. In addition there is a dwellperiod at the position where the tube walls are closest together,improving the action of the pump.

FIGURES 7 and 8 illustrate a modified form of tube 50 which has a lining51 compatible with the fluid being pumped. The tube may also includereinforcing material, such as a synthetic fibre braid, indicated at 52.This enables the tube to withstand higher pumping pressures withoutmaking the wall of the tube very thick. The

4 reinforced tube will also withstand more arduous working conditions.

As stated above, as the return of the tube from its distorted conditionto its undistorted cross-section is positively produced by thereciprocating action of the pressure bars 24 and 25, the resilience ofthe material forming the tube is not a pertinent feature. Tubes ofmaterial having little or no resilience can be used, and may bepreferred as the power requirement for distortion of the tube isreduced.

It will be appreciated that a pump according to the present invention isparticularly useful as a peristalic pump for pumping blood, for example,such as in artiiicial heart and lung machines.

A further and very important advantage of the present invention is thatit is very quick and easy to replace the actual pumping member, thetube. Both in medical and in other practices it is often necesary tosterilizethe tube. In certain circumstances the tube may becomecontaminated with undesirable or dangerous materials. It will be seenthat the pumping member is very quickly and easily removed, providingready disposal, or decontamination or sterilization, as the case may be.Also, pumping members of differing materials can readily be interchangedfor the pumping of different materials.

I claim: 1. A fluid pump comprising: a flexible tube; a series of pairsof opposed action reciprocable pressure members positioned along saidtube at spaced apart locations, one of each pair of members on one sideof the tube and the other of each pair of members on the other side ofthe tube; means attaching said members to the wall of the tube; meansfor reciprocating successively the pairs of pressure members toprogressively distort the tube to an occluded condition and toprogressively restore the tube to an undistorted cross-section, saidmeans comprising a rotatable cam member having a series of pairs ofopposed cam surfaces on said member, the pairs of cam surfacesprogressively displaced about the axis of rotation of the cam member, aseries of reciprocating members, one for each pressure member, and meanson each reciprocating member for engagement with a related cam surface;

each reciprocating member including; a first extension extending in adirection from said cam member toward said tube, a pressure memberattached to the end of each said first extension; and a second extensionextending in a direction opposed to said first extension and having atleast one guide surface extending generally in the same direction assaid second extension; and

guide means extending parallel to said cam member,

said guide surfaces on said second extensions cooperating with saidguide means.

2. A pump as claimed in claim 1, including radially extending fins onsaid tube, diametrically opposed and extending parallel to thelongitudinal axis of the tube.

3. A fluid pump as claimed in claim 2 wherein holes are formed in saidfins, said pressure members extending through said holes.

4. A fluid pump as claimed in claim 3, said fins laterally displaceableon said pressure members for removal from and replacement on saidmembers.

5. A fluid pump as claimed in claim 1 wherein the rotatable cam membercomprises a rotatable camshaft provided with a pair of cams for eachpair of pressure members, the cams in a pair displaced substantiallyabout the axis of rotation of the camshaft, and each pair of camssuccessively displaced about the rotational axis of the camshaft.

6. A fluid pump as claimed in claim 5 wherein the tube extends in linewith and is spaced parallel to the camshaft.

7. A fluid pump as claimed in claim 1 wherein said reciprocating membercomprises a plate member, said plate member defining a cam slot forcooperation with a cam.

S. A fluid pump as claimed in claim 1 wherein said guide means is arotatable bar, mounted for eccentric rotation, said bar extending inline with and parallel to said cam means, rotation of said bar varyingthe angular disposition of said reciprocable pressure members relativeto said cam means.

9. A fluid pump as claimed in claim 8 including further guide means forsaid first extension on said reciprocable members.

10. A fluid pump comprising an elongated hollow housing, said housinghaving side and end walls and closed at one end with a cover; a camshaftextending through said housing and mounted for rotation in said end walland said cover; a series of pairs of cams on said camshaft, the camsforming a pair displaced substantially 180, the pairs of cams positionedat spaced apart intervals and progressively angularly displaced alongthe camshaft; a series of reciprocable members mounted one on each camfor reciprocation thereby; a support positioned in a side wall of thehousing and extending longitudinally in the housing in line with saidcamshaft; a series of guide holes in said support; a first extension oneach of said reciprocating members, said extensions extending throughsaid guide holes; a pressure member at the end of each said firstextension and extending normal thereto, said pressure members spacedapart on either side of a plane parallel to the axis of rotation of saidcamshaft for the reception of a flexible tube therebetween; a secondextension on each of said reciprocating members, said second extensionsextending in a direction opposed to said first extensions, and at leastone guide surface on each said second extension extending generally inthe direction of the second extension; guide means in said housing forcooperation with said guide surfaces on said second extensions; aflexible tube supported between said pressure members and having meansfor connecting one end of said tube to a fluid source and the other endto a fluid supply and means for connecting said pressure members to saidtube, whereby on rotation of said camshaft the tube is progressivelydistorted to occlude the tube bore and progressively restored to anundistorted cross-section.

11. A fluid pump as claimed in claim 10 wherein said guide meanscomprises a bar mounted for eccentric rotation in said end wall and saidcover; each said second extension defining a slot for cooperation withsaid bar; and means for rotating said bar; whereby the angulardisposition of said reciprocating members relative to said camshaft isvaried.

12. A fluid pump as claimed in claim 11 wherein each said reciprocatingmember comprises a plate, said plate defining a slot for cooperationwith the related cam.

13. A fluid pump as claimed in claim 10 wherein said tube has twodiametrically opposed fins extending radially in the same plane andlongitudinally of the tube, said fins defining holes therein for thereception of said pressure members.

14. A fluid pump as claimed in claim 13, said fins laterallydisplaceable on said pressure members for removal from and replacementon said members.

15. A fluid pump as claimed in claim 10 wherein said tube has a liningof material which differs from the material of the tube.

16. A fluid pump as claimed in claim 10 wherein the tube is reinforcedby fibrous material in the wall of the tube.

References Cited UNITED STATES PATENTS 1,922,196 8/1933 Butler l03--1522,105,200 1/ 1938 Phelps 103--l49 2,546,852 3/1951 Comeil 103--1482,689,530 9/1954 Harvey 103-148 2,877,714 3/1959 Sorg et al 103-1493,083,647 4/1963 Muller 103-148 3,176,622 4/1965 Pfeitfer 103149 FOREIGNPATENTS 961,579 5/ 1950 France. 836,006 4/ 1952 Germany.

DONLEY J. STOCKING, Primary Examiner.

LEONARD H. GERIN, Assistant Examiner.

US. Cl. X.R. l03l52

